|Publication number||US6864876 B2|
|Application number||US 09/725,959|
|Publication date||Mar 8, 2005|
|Filing date||Nov 30, 2000|
|Priority date||May 1, 2000|
|Also published as||DE60040728D1, EP1152277A2, EP1152277A3, EP1152277B1, US20010035846|
|Publication number||09725959, 725959, US 6864876 B2, US 6864876B2, US-B2-6864876, US6864876 B2, US6864876B2|
|Inventors||Jong-woo Shin, Soon-cheol Kweon, Hyung-jae Shin|
|Original Assignee||Samsung Electronics Co., Ltd.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (16), Referenced by (1), Classifications (9), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates to a micro-mirror device for an image display apparatus which can change the traveling path of incident light by pivoting a mirror that is installed to correspond to each pixel and, more particularly, to a micro-mirror device for an image display apparatus and method which can increase optical efficiency by pivoting a mirror in the direction of the sides of the mirror.
2. Description of the Related Art
In general micro-mirror devices for an image display apparatus include a plurality of mirrors that are installed to be driven by an electrostatic force to reflect incident light at a predetermined angle. These micro-mirror devices are used in image display devices of projection televisions, and optical scanning devices such as scanners, photocopying machines, and facsimiles. In particular, when these micro-mirror devices are used in image display devices, the number of mirrors equals the number of pixels arranged two-dimensionally, and each of the mirrors is driven in response to an image signal for a corresponding pixel, thus reflected light has varying paths of travel resulting in the formation of a picture.
When the micro-mirror device having the above-described structure is adopted in an image display apparatus, a plurality of micro-mirror devices are arranged in two-dimensional array structure, as shown in FIG. 2. The micro-mirror devices, arranged as described above, are driven around a rotating axis positioned on a diagonal line, resulting in shapes of the micro-mirror devices being projected as shown in
To solve the above problem, an objective of the present invention is to provide a micro-mirror device for an image display apparatus having an improved structure, and a method of using the same, where a mirror is pivoted in the direction of its sides.
The above objective of the present invention is achieved by a micro-mirror device for an image display apparatus, including: a substrate; a landing pad provided on the substrate; a pair of base electrodes provided on opposite sides of the landing pad; and a pair of first posts protruding from the upper surface of the landing pad that are isolated from each other by a predetermined interval. The invention further includes a girder which is supported by the pair of first posts and is pivoted toward the sides of the landing pad by an electrostatic attraction; a second post protruding from the upper surface of the girder; and a mirror which is supported by the second post that reflects incident light, and receives power via the landing pad. The mirror is pivoted toward the sides of the landing pad by the electrostatic attraction between the base electrodes and the mirror.
A method of reflecting light using a micro-mirror device in an image display apparatus is also contemplated. The method comprises supplying a driving voltage to at least one of a pair of base electrodes of the micro-mirror device and creating an electrostatic attraction between the at least one of the pair of the base electrodes and a mirror, wherein the mirror is pivoted around an axis formed in a lengthwise direction of the pair of base electrodes. The method further includes altering the driving voltage which is supplied to the at least one of the pair of base electrodes so that a reflection angle of light incident upon the mirror is controlled.
The above objective and advantage of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings, in which:
The pair of base electrodes 115 are separated by a predetermined distance from each other on the substrate 110, with the landing pad 113 therebetween. The base electrodes 115 are formed to a predetermined length on opposite sides of the substrate 110, respectively, so that an electrostatic attraction is exerted upon opposite sides of the mirror 151. The landing pad 113, on which the pair of first posts 131 are installed, also acts as an electrode for applying power to the mirror 151. Hence, the electrostatic attraction is generated between the base electrodes 115 and the mirror 151, when power is applied to the base electrodes 115 and the landing pad 113. The generated electrostatic attraction rotates the mirror 151. Preferably, each of the base electrodes 115 has an inwardly-protruding portion 115 a to increase the area that faces the mirror 151, so that a driving force due to the electrostatic attraction is increased.
The pair of first posts 131 protrude vertically, a predetermined amount, from the landing pad 113 and are isolated from each other by a predetermined distance. The pair of first posts 131 also act to support the girder 120. The girder 120 is installed so as to pivot toward the sides of the landing pad 113 by the electrostatic attraction, and has a rotating axis that is formed in a direction equal to a lengthwise direction of the base electrode 115.
The girder 120 includes a support plate 121 for supporting the second post 141, and a pair of springs 123 that connect the support plate 121 to the upper surface of each of the first posts 131 and pivotally support the support plate 121.
The support plate 121 has connecting portions 121 a which protrude from the sides of the support plate in a direction parallel to the lengthwise direction of the base electrodes 115. The connecting portions 121 a are point symmetrical to each other with respect to the cross-section of a portion contacting the second post 141. Each of the pair of springs 123 connects the upper surface of each of the pair of first posts 131 to each of the pair of connecting portions 121 a. The springs 123 receive opposite elasticities due to the electrostatic attraction between the mirror 151 and the base electrodes 115. Accordingly, when the mirror 151 is pivoted vertically by the electrostatic attraction, the pair of springs 123 are rotated in opposite directions. Also, when the direction of pivoting is changed, the directions of rotational moments applied to the springs 123 are also changed. Each of the springs 123 receives both upward and downward elasticities, so that the elasticity coefficient of each spring 123 does not change.
Preferably, the girder 120 further includes landing tips 125 protruding from opposite sides of the support plate 121 in a direction corresponding to the direction of pivot of the support plate 121. The landing tips 125 are inclined to approximate a point contact with the landing pad 113. Also, the landing tips 125 are formed to be thinner than the support plate 121 so that their ends are elastically deformed when contacting the support plate 121, thus achieving shock-absorption. Also, elastic energy is accumulated when the landing tips 125 are elastically deformed, and the accumulated elastic energy is changed into kinetic energy for the girder 120 and the mirror 151, when the mirror 151 is restored to its original location by removal of the driving voltage. Consequently, adhesive contact of the mirror 151 with the base electrodes 115 is prevented, and contact of the girder 120 with the base electrodes 115 is smoothly removed.
The second post 141 protrudes a predetermined amount above the center of the support plate 121, and supports the center of the mirror 151. The inclination angle of the mirror 151 depends on the electrostatic attraction, which changes the reflection angle of light incident upon the upper surface of the mirror 151. Here, the height of each of the first posts 131 is lower than that of the second post 141. Accordingly, the girder 120 contacts the landing pad 113 instead of the sides of the mirror 151 making contact with the base electrodes 115.
In one embodiment, the micro-mirror device 100 is adopted in an image display apparatus, and a plurality of micro-mirror devices 100 are arrayed in a two-dimensional structure, as shown in FIG. 7. The plurality of micro-mirror devices 100 are driven on their sides on the basis of a rotating axis. When the micro-mirror devices 100 are driven as described above, the projected shapes of the micro-mirror devices 100 are as shown in
In the micro-mirror device for an image display apparatus having the structure described above, pivoting of the mirror 151 using the rotation moment of the girder 120 determines the traveling path of light, so that an optical arrangement of an optical system such as a projection lens is easily made. Thus, the sideward driving of the micro-mirror devices 100 enables the control of the area ratio of the micro-mirror device array and the horizontal/vertical power ratio of radiated light, which leads to the high optical efficiency.
It is contemplated that numerous modifications may be made to the apparatus and method of the present invention without departing from the spirit and scope of the invention as defined in the claims.
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|U.S. Classification||345/108, 345/204, 345/84, 345/85, 345/55|
|International Classification||G02B7/182, G02B26/08|
|Mar 1, 2001||AS||Assignment|
|Sep 3, 2008||FPAY||Fee payment|
Year of fee payment: 4
|Aug 27, 2012||FPAY||Fee payment|
Year of fee payment: 8